The present invention relates to a process for the manufacture of wear parts having a relatively large wear surface area, and the product formed thereby.
In woodworking and other industries employing machinery having relatively large surface area wear parts such as bed plates for planers or the like; the wear parts frequently become worn within a relatively short period of time and require frequent replacement. This results even though efforts have been made to surface harden the parts or manufacture the parts with chill cast iron or hard metals. In some cases, the wearing surface of the large surface area parts have been chrome plated to attempt to increase their wearability. Although these efforts have resulted in a somewhat increased life as compared with untreated surfaces, the parts so treated still wear out with undesirable frequency.
It has long been recognized that tungsten carbide material provides an excellent wear surface with durability far surpassing other wear surfaces. In order to tungsten carbide plate relatively large surface areas, however, the temperature required is in the order of 1,300.degree. F. This temperature is necessary when for example, tungsten carbide plating a wear surface to a thickness of approximately 1/16 inch. When heating a relatively large area bed plate or the like to such temperatures, warpage becomes a tremendous problem. As the wear part cools after the plating process, the wear surface will generally be uneven due to the warpage. With only 1/16 inch thickness conventionally capable by tungsten carbide plating, the surface cannot normally be flattened by grinding while still maintaining the desired protective cover. Thus, efforts to tungsten carbide plate large surface wear parts has generally not been successful.
To overcome the difficulties in tungsten carbide plating large surfaces, tungsten carbide tiles have been employed by brazing the tiles directly to the wear part at relatively high temperatures (1300.degree. F. or higher) thereby providing a thick tungsten carbide protective cover with the resulting matrix of the tiles. In such an attempt, however, the high temperature causes the same warpage problems encountered with tungsten carbide plating resulting in an uneven surface which must be ground considerably to achieve the desired flatness. In addition, due to the relatively large area encountered, the high temperature brazing process is extremely time consuming and dangerous to personnel attempting to cover a wear part using such a process. Also, the amount of grinding necessary to achieve a flat surface considerably reduces the effective protective surface of the tiles since considerable material must frequently be ground away.
To overcome the difficulty of the high temperature brazing of tungsten carbide tiles on large surface areas, an attempt has been made to employ a bonding adhesive such as epoxy to hold the tiles on the surface of the wear part. Although this process overcomes the difficulties of warpage and hazardousness to the personnel, the adhesion has not been satisfactory under the high shear forces encountered by the parts during usage. Frequently, during use a tile loosens from the wear part due to the inadequate bonding achieved.
Thus, the attempted known methods have been inadequate to provide wear parts having large wear surfaces which are extremely durable and long-lasting. Conventional plating and the like does not provide the protective coating achievable with tungsten carbide plating while plating and known methods of adhering tungsten carbide tiles to wear surfaces have not proven adequate or commercially feasible.